A:AnswerYes you can just leave one in the case and use the other one, whichever one is inside the case will not play so you can use whichever one you want if you don’t want to use both at the same time
A:AnswerIt probably is just connecting to your phone on Bluetooth. Mines transfers from my car, or other Bluetooth devices, to my headset sometimes. Idk if you can change something in your setting